Method and means for purifying lubricating oil



March 9, 1937.

2 sheets-sneet'l Filed Jan. 2, 1935 ..5 n Il f l l Il r fr: I lnIlIffll/IAllllllfllllllllla e I Il 21,: ,555.9552251252.,z2 5.552.251,71:..-51.

March 9, 1937. l K s. 'w. BRIGGS 2,073,442

l METHOD AND MEANS FOR PURIFYING LUBRICATING OIL Filed Jan. 2, 1935 2 sheets-sheet 7l. .95 7.0 76 f0.7 703 z;

Patented Mar. 9, 1937 NITED STATES, Mqgiq'rorricls l* METHOD AND MEANS Fon PURIFYING f LUBBICATING on.

4Southwiclt W Briggs, Washington, D. C. Application January 2, 1935, serial No. 163

z claims. (ci. 21o-134) l This invention relates generally to the purification of lubricating oil during use thereof `in an engine, and more particularly in the lubricating system of an internal combustion engine, es- 5 pecially an automobile engine.

The. principal objects of the invention are the provision of a new means for purifying lubricating` oil under such conditions. l In the use of internal combustion engines on automobiles it is common practice to circulate some of the oil from the crank case under pressure through itering material and back to the crank case. While the quantity of oil thus cir- 15 culated through the filtering medium is relativefly small, yet the continued circulation of oil while theengine is running soon passes the entire volume of oil in thelubricating system through the filtering medium and does so repeatedly. Cotton 20 fiber in the form of waste h as been suggested as a filtering material. Fullers earth, when employed in the manner set forth in my Patent 1,860,229, granted May 24, 1932, has been successfully and extensively used.

25 According to the method and .meansof' thel present invention, improved results are realized by circulating the oil under pressure through both a suitable fibrous material such as cotton waste,.and a suitable adsorbent material such as fullers earth, among the important" advantages being that each material removes some of the impurities, especially those which it is best adapted to remove, and that removal of some of tively in removing other impurities which are not removed or removable by the fibrous material. The invention and the aforesaid and other ob- 40 jects and advantages realized thereby will be` fully understood by reference to the embodiments thereof shown in the .accompanying drawings and to the fol-lowing detailed description in connectionwith said drawings, wherein- 45 Figure 1 is a vertical sectional view, with parts shown in elevation, o f one embodiment of the -55 Fig. 5 is a vertical sectional view, with parts and useful method of and the impurities by the fibrous material makes it possible for the fullers earth to act more eiiecin section, of another embodiment ofthe invention; f

Fig. 6 is a detail perspective view of one of the straps shown in Fig. for securing the vfilter inplace on an automobile; and Fig. 'I is a detail view, partly insection,vshow ing the use of a check-valve in the oilyfeed'line of Fig. 1. j

Referring to Figs. 1 tc 4-III is-an outer casing or jacket of cylindrical form closed at its lower projecting annular flange I2 around its open upper end, the upper surface of said flange constituting a seat against which other parts presently described are secured to form a liquid tight joint at the top of the casing. The casing I0, -its bottom I I and the ange I2, are preferably integrally formed from a single, piece of sheet steel by stamping or other well knownmethod. Casing I0 may be supported in any suitable manner in convenient relationship to anlengine with which it is tobe associated. For example, it may be mounted on the engine itself, or, as shown in Fig. 1, it may be provided with bracket I3 andthe latter secured tothe dash I4 of an automobileby bolts I5, I5, engaging nuts I6, I6', the latter being preferably spot-welded to the bracket I3.'

(known as the ,oi1 return line) I1 is a pipe for conducting filtered oil from the fliterback to the engine. At its upper end'pipe-IT is secured in a pipe joint I8` the upper end of which is screw-threaded upwardly through .an opening I9 in flange I2 of the casing and made ush with the upper surface of said flange (Figs. 1 and 2).

An annular gasket or packing`20, of the 'same external diameter' as flange I2, ts against the upper surface of said flange and has therethrough .an opening 2I registering with the opening I9 -in the ange and4 alsojwith the upper end of the passage through pipe joint I8. An annular disk22 of sheet steel, of the same external diameter as flange I2 and gasket 20, fits against the upper face of ,the latter and has' an opening 23 therethrough registering with opening 2| through said gasket. The'central space in disk 22 is covered by a screen 24 positioned against the bottom surface. of a circular perforated plate 25, said -screen and platel being secured or clamped in place around theinperipheral edges by airing 26 of approximate S-shape in crosssection, as best shown in Fig. 2. Disk 22 with the screen 24 and perforated plate 26 together constitute what' is termed the filter-head." The screen 24 is preferably of Monel metal and of fine-mesh, say about -#140, which is about kend by bottom wall I-I and having an outwardly one-twelfth the size of the particles or granules of the fullers earth mentioned hereafter. The presence of this screen is principally an emergency provision to stop any small particles of the fullers earth or other solid matter that may be' come suspended in the oil before it passes through the screen to the outlet from the filter.

21 is another annular gasket seated against the upper surface of disk 22 and of the same outside diameter as said disk. Gasket 21 away, or slotted, at 28, the outer extremity of this slot being rounded and registering with the opening 23 in disk 22. 29 is 'the circular cover for the casing which is of the same exterior diameter as the gasket 21 and fits against the lafof bolts 38 spaced apart entirely around the casing and each extending through registering openings such as 3| (in flange I2), 32 (in gasket 2l). 33 (in disk 22), 34 (in gasket 21) and a correspondingly positioned opening in cover 29, securely bind all of said parts together to form a liquid-tight joint between said cover plate 29 and the flange I2 of thecasing, with the exception of the liquid outlet passage leading from the space immediately beneath the cover radially through the slot 28 of gasket 21 and thence downward through openings 23 and 2| and through tting T-coupling 36, the upper branch of which engages the lower end of a threaded nipple 31 which passes through an opening in the center of the bottom II of the casing. The upper'end lol nipple 31 is engagedby a relief valve '38 located inside of the casing and of well-known standard construction including a tubular inlet plug, a ball valve seated against the inner end of said plug, a coiled spring acting at one end upon said valve, and a plug against which said spring seats at its other end.

A pipe 39, a small part only of which is shown in Fig. 1, is connected at its upper end by a pipe joint 40 to the lower branch` of T-coupling 36 and at its lower end by a pipe joint 4I to the interior of the crank-case of the engine through a portion of the wallof said case shown at 42. A nipple 43 threaded through an opening in another part 42 of the crank-case wall is engaged at its upper end by a T-coupling 44. A pipe 45 (known as the is joined to the upper branch of said coupling and leads to oil gauge 46 at a suitable location. A pipe 41 (known as the -feed line to the filter) is connected at its lower end to the side branch of T-coupling 44 by a pipe joint 48 having therethrough a small passage 49, preferably a. #50 drill hole, which is a hole of an approximate diameter of 7/ 100 of an inch. At its upper end pipe 41 is connected to an elbow 50 by a pipe joint 5|. A nipple 52 (similar to nipple 31) is screw-threaded at one end in an opening through the side wall of casing IIJ and at its other end into the elbow 50. 'Ihrough the connections thus described the pipe or .feed line" 41 conducts oil under pressure from the crank case or lubricating system to the interior of outer casing I while the engine is running.

A drain -opening through the bottom wall II of the casing is closed by a removable screv.- threaded plug 53. A short section of flexible tubing 54 (of suitable material, such as Duprene), as shown in Fig. 3, may be interposed is cut by suitable connections in each of the pipes 41 an'd 39 and serve, when the filter is mounted on the dash, to absorb vibrations between the parts rigidly attached to the crank-case and filter respectively. The use of such flexible tubing is unnecessary when the lter is mounted on the engine; The pipes I1, 39, 45 and 41 are preferably inch copper tubing; and the pipe joints I8, 35, 40, 4I and 5I are preferably inch com- I known standardl construction. Pipe joint 48, having a #50 drill hole, is also preferably. a compression tting.

As readily appears, removal of the bolts 3l permits removal of the cover 29 and associated parts which close the upper end of casing III, thus giving access to the interior of said casing. (for removal and replacement of the inner receptacle orrefill, or for other purpose) without disconnecting or otherwise disturbing any of the connections to the lter for pipes leading to and from the same and without disturbing the mounting of the filter on the automobile. 0n this point the connecting of the oil return line or pipe I1 with the opening I9 through the flange I2 by means of the pipe joint I8 is of special importance; and in respect thereto the present application is a continuation-impart of my earlier application led July 27, 1933, Serial No. 682,507.

I Within the outer casing III, there is an inner l cylindrical removable receptacle or container 55 (such as a tin can) for the filtering material. said container being permanently closed at its top by a perforated end plate 56 and the periphspaced aroundsaid contents (above to presses the latter upengages against the cover 29 thereof is removed.

The inner 63 (such as shellac or preferably bakelite, varnish or silicate of soda) which should be impervious to the oil to be filtered. 64 is a relatively comfibrous filtering material filling the the container, bearing against the cover 51 and extending across the perforations therein, vand attached to the side wall by the adhesive 63. -The perforations in the cover are such as to freely admit oil under pressure while at the same time preventing escape of fibrous material therethrough when the engine stops (theresurface of the vertical cylindrical wall of container 55 is covered with an adhesive waste, which as marketed is wound in skeins or` loops, has been found to be of considerable advantage over ordinary waste, both as to handling and effectiveness in filtering. The. skeins are cut across and several of' them wound spirally into a roll with the ends at the cuts slightly overlapping, as shown in Fig. 4, thus producing a fibrous body or mass of approximately uniform or even density which can be readily handled and put in place in the container. Forming the fibrous material into a roll increases its resistance to excessive compacting endwise, such as `might obstruct the desired freedom of passage of the oil therethrough. l

Highly satisfactory results have also been obtained by using as the brous material 64 a suitable absorbent wood pulp product, preferably crepe paper, plies or layers of which may be superposed and one or more bundles of the plies then spirally wound into rolls similar to that shown in Fig. 4.

In whatever form the fibrous material 64 is used, the securing thereof to the side wall of the container by adhesive 63 has several important advantages.. For example, it resists undue compacting of the fibrous material and excessive obstruction to the flow of the oil that might result from such compacting; it resists tendency of the fullers earth to work down the side wall of the container between the same and the fibrous material; and it permits upward movement of the central portion of the fibrous material, under upward pressure of the oil, while at the saine time preventing the peripheral portion of said fibrous material from being drawn away from the side wall ofthe container. Thus the securing of the fibrous material to the side wall of the container prevents several conditions any one-or more of which might, and probably would, interfere with the proper passageA of the oil under pressure through the filtering materials and the proper functioning ofthe filtering means or device as a whole. Said upward movement of the fibrous material under upward pressure of the oil serves an important function in connection with the overlying fullers earth as explained hereafter.

65 is a body of suitable adsorbent ltering or refining material, preferably fullers earth, nearly of the mass 65 being embedded in the adhesive Y 63 in accordance with the invention of my previously mentioned patent. In the construction shown lin Fig. 1 it hasbeen found preferable to employ the fibrous material 64 and the fullers earth 65 in about equal proportions by volume: but these proportions may be 'varied according to the particular filtering materials employed. In the use of two kinds of filtering material as shown, the fullers earth 65 is preferably introduced in place in an unpacked condition, thus saving the expense of packing and also avoiding the formation of fines or pulverulent earth due to packing. The presence of such fines in a construction of the kind illustrated would, it is believed,

conduce to channelling of the oil through the of the inner surface of the container.

fuuerfs earth and also unduly obstruct the now of oil therethrough. Furthermore, in the construction shown, the before mentioned upward movement of the fibrous material 64, caused by upward pressure of the oil, serves to impart evenly distributed pressure to the body of fullers .earth 65, thereby tending to evenly compact the same and also take up any settlement therein such as might otherwise result from jarring or vibration occurring before or after the filter is put in service;

When fullers earth constitutes the entire filter- `ing body, as in my above mentioned patent, and

is relied upon both to mechanically filter or strain outv of the oil impurities such as particles of carbon and dirt and also to remove by adsorption impurities such as acids, resins and asphaltic matter, it is desirable to employ a grade of fu1lers` earth composed of relatively fine particles, such as the 30--60 proportion 'or mesh mentioned in said patent. But when, as in the present invenf tion, l.the fibrous material 64 is mainly relied upon engine is started and be promptly'followed by cil sufiiciently heated by the engine to quicklyheat i the filtering materials, especially the fullers earth, to an eiiicient operating temperature. Thus, the

coarser fullers earth affords not only the ad vantage of more free and hence speedy circulation of theI oil therethrough during normal running of thel engine, but also provides for better operation, especially in cold weather, upon starting the engine with the oil cold'or congealed.

' Above the fullers earth 65 and filling the vspate between the same and the perforated end 55 of the container, there is a pad 66 of fibrous material, such as ordinary cotton waste, which is attached to the side wall of the container by the adhesive 6.3. This pad prevents particles of the fullers earth from passing out of the container withfthe filtered oil and also prevents abrasion of the fullers earth (with the formation of fines) by contact with the perforated plate 56.v

In the absence of the pad 66, abrasion might occur in shipping and from other conditions producing relative movement between the fullersV earth vand the metal plate.

The container 55 Iisjiilled by placing it, open end up, on a table orother support with its cover 51 removed. -Adhesive 63 is then applied over part 66 is then put in place andthe fullers earth 65` poured in over the pad, no special packing or compacting of` the fullers earth being required as before explained. More adhesive 63 isthen applied over the rest of the inner surface of the container and the roll of fibrous material 64 is then introduced and forced into place under 'considerable pressure. The cover 51 is then applied 2l and cover 29 are then put in position and the vparts secured together by bolts 30, with the spring 59 compressed and hence under tension.

The pad Fullers earth is very hygroscopic. As mined it is said to contain in the neighborhood of 23% of moisture or water, this being reduced to about 17% by air drying and crushing. Its efficiency as an adsorbent filtering or refining material for the purpose of this invention increases with decrease of moisture content. Therefore it is de' sirable to still further reduce the moisture content and it has been found that reduction to about 5% can be accomplished without great difliculty by drying in an oven. To preserve this low moisture content of the fullers earth by protecting it from absorption of moisture from the atmosphere duringhandling and shipment ofthe filled container 55 or refill, I saturate or soak the fullers earth with asuit-able oil, such as the lubricating oil eventual/1y to be'circulated through the fullers earth for filtration. It is preferable to soak the fullers earth with the oil after the earth is put in the container, but this may be done before.

The fiow or circulation of oil in the construction shown in Fig. l is as follows: Oil from 'the lubricating system is forced under'pressure, when the engine is running, from the crank-case at 42' through the restricted passage `45|, pipe 41 and elbow 50 into the casing I0 which becomes filled around the container 55. Oil is then forced upward through perforated cover 51, fibrous filtering material 64, fullers earth 65, brous pad 66, space 6|, screen 24 and perforated plate 25,

`into the space beneath cover 2,9, and thence through passage 28, pipe I1, T-connection 31 and pipe 39, back to the crank-case at 42. If oil is delivered into the casing I faster than it can circulate through the container 55 and the filtering material therein, the pressure of the oil becomes suiiicient to open the relief valve 38 at the bottom of the casing v|0 and permit the excessive supply of oil to be conducted (by passed) through pipe 39 back to the crank-case at 42. The upward pressure of the oil entering the bottom of the container 55 imparts upward movement to the fibrous material 64, which in turn moves upward against the fullers earth 65, as

f before described, and presses the latter upward into a relatively compact mass against the pad of'waste 66.

Oil forced under pressure from the lubricating system of the engine into the filter, is 'chargedwith air 'in substantial volume, which results from scattering and throwing of the oil about in the crank case by the rapidly rotating and vibrating parts of the engine, such as the pistons, connecting rods, crank shaft and its cranks.v The air with which the oil is thus charged being elastic becomes somewhat compressed in the filter and its filtering material. When the engine stops and thus discontinues the oil pressure on the intake or feed side of the filter, the compressed air expands and causes a reverse or back ilow or back-wash of oil which may extend back into the feed pipe 41 and be of such force as to disrupt or dlsarrange the filter bed, especially the Jdy of fullers earth. When the engine is again started and the pressure of the oil thus resumed,

the brous material 64 again moves upward against the fullers earth 55 and thus acts to restore the proper operating condition of the lter bed.

It is preferred, however, to substantially avoid or limit such sudden expansion of the compressed air andthe eiects thereof, by providing a. suitably located check valve. This isy shown in Fig.

, 7, which is a modification of part of the conlocated in the pipe joint or compression fitting |04 (corresponding to pipe joint 5| in Fig. l) which is threaded into elbow 50, and a tubular plug |05 is screw-threaded into the end of the fitting |04. A spring |06 bears at one end against plug |05 and at its other end against a ball valve |01, tending to hold the ball seated over an opening |08. When the engine stops and thereby discontinues the pressure on the under side of ball valve |01, said valve is immediately seated or closed by the reverse flow of oil and thus prevents back-wash. A

'Ihe modified construction shown in Fig. 5 dispenses with an outer casing such as shown in Fig. 1, there being a single cylindrical container or receptacle 10 (such as a tin can) closed at its ends by caps 1| and 12, respectively. The peripheral edge of each cap and the corresponding edgeof the side wall are seamed or crimped together in well known manner to make tight joints at 13 and 14. Adjacent the joint 13 cap '1I has an annular flat portion 15 surrounding an outwardly bulged middle portion having an opening through the center thereof with an interiorly screw-threaded reinforcing sleeve or bushing 16 secured in said opening. Cap 12 is similarly formed with an annular fiat portion 11 surrounding an outwardly bulged middle portion having through the center thereof an interiorly screwthreaded reinforcing sleeve or bushing 18. The container 10 is shown in Fig. 5 as being mounted on dash 19 of an automobile by means of two metal straps 80, such as shown in Fig. 6, with small bolts 8| passing through the dash and a hole 82 in each end of the straps.

83 is a portion of the wall of a crank casinghaving therethrough a screw-threaded outlet opening engaged by one end of a nipple 84 (similar to nipple 31 of Fig. 1') the other end of which is threaded into the lower branch of a T-coupling 85. A pipe 86 connected by a pipe joint 81 to the upper branch of coupling 85 leads to an oil gauge 81' suitably located for observation. A pipe 88 (known as the feed line" to the oil clari'er) is connected at its lower end to the side branch of T-coupling 85 by a. suitable pipe joint 89 having therethrough a small passage 90 for limiting the flow of oil, preferably a No. 50 drill hole. AtV

its upper end pipe 88 is connected to the bottom of the casing by means of a suitable pipe joint 9|, the screw-threaded upper end of which engages the screw-threaded opening through bushing 18.l A pipe S2 (known as the return line) is connected at its upper end to the interior of the casing by means of a pipe joint 93 having a screw threaded end which engages through bushing 16 of the end cap 1|. 'At its lower end pipe 32 communicates with the interior of the crank case through a. pipe joint 34 the lower end of which is screw threaded into an opening through a part 03' of the wall of said crank case.

The inside surface of the cylindrical wall of the container is covered with a suitable adhesive 35, such as silicate of soda. A circular screen 36 fits closely within the casing at the bottom thereof, rests against the shoulder formed by annular hat portion 11 of cap 12, and provides an open space 01 between its bottom surface and the cap 12. A body of fibrous material 08 bears upon screen 90' and fills the casing transversely and vertically to a height somewhat less than one-half of the height of the interior of the casing. At its periphery the body of material 9| engages the adhesive 35 and is attached by the latter to the vertical wall of the casing. A body of fullers earth 99 rests against the fibrous material 98- and fills the casing transversely and vertically above material 98 to near the top of the casing. As shown, the depth of the fullers earth 99 is about the same as that of the fibrous material 98. At the periphery of the body of fullers earth .the particles thereof engage the coating of silicate of soda 95 and are attached thereby to the wall ofthe casing. Above the fullers earth there is a relatively shallow layer or pad of fibrous material |00, such as ordinary cotton waste, which pad is also attached at its periphery to thewall of the casing by engagement with the adhesive coating 95. Immediately above the pad of waste there is a circular wire screen |0| and above the latter a circular perforated plate |02 which bears against the annular shoulder formed by the at portion 15 of cap 1|. Between the plate |02 and thecap 1| there is an open space |03. The screens 96 and |0| may be ordinary steel vy screening of a mesh, say about 1*; in ch, suitable for keeping particles of waste from the pad |00 from passing out with'the filtered oil `and for supporting the-body98 of fibrous filtering material.

The circulation of oil from the engine through the filter in Fig. is very much the same as hereinbeiore described in reference to the lter of Fig; 1. Oil is forced under pressure from the crank case at 83 through the feed line 80 into the space 91 at. the bottom of the filter; thence through screen. 96, fibrous filtering material 98,- fullers earth 99, 'screen |0| and perforated plate |02 into space |03 at the top of the filler; andv thence through the pipe or return line 92 back to the crank case at83'. Upward movement imparted to the fibrous material 98 by the oil pressure acts upon the fullers earth above in the samemanner as explained in connection with Fig. 1.v The feed line 88 of Fig. 5 may be provided with a check valve similar to that shown inFig. 7 and for the same purpose.

In describing the action and cooperation .of the brous material and the fullers earth in removing impurities from the oil circulated therethrough, it is appropriate to begin by referring to the character of those impurities. It is well known that oil used in lubricating systems of in. ternal combustion engines, especially on automobiles, tends to become contaminated with various impurities with consequent diminution of the lubricating property and value of the oil. Thevariety of such impurities, the sources from which they become present inthe oil, and their injurious effects upon the oil, are generally indicated bythe following quotations from accepted authorities', to wit:

Chemical Refining of Petroleum, published 1933, by Vladimir A. Kalichevsky-Research Laboratory, Socony-Vacuum Corpn., and Bert Allen Stagner, formerly Supervisor of Chemical Research, Union Oil Company, on page 335 states:

When used in an automobile engine, a lubricating oil not only becomes contaminatedI with z the higher boiling constituents of gasoline and coke-like products from the combustion chambers, dust from roads, and worn fragments from the bearings, but some of the oil itself slowly undergoes partial oxidation from contact with the air and eventually forms deleterious products in sufcient quantity to render further use of the oil unsafe. In the oxidation are found organic acids, which attack the metal parts of the motor and produce metal soaps insoluble in oil, and other oxidation 'products which undergo transformaimpurities.

tion by polymerization, condensation, etc. into senil-solid gum-like material, for the `most part insoluble in the oil. The material separating from the oilis known as sludge.

Automobile Engine Lubrication Oils" by,Bu reau of Standards (March 22, 1934) on page 3 states:

Due to their'instability under service conditions, all motor oils undergo certain changes during use. The changes occurring are: (1) cracking, or decomposition of the oil into lighter coml ltration; and, second, acids, resins, asphaltic matter, etc., which are removable by adsorption filtration or refining, but not by mechanical filtration. I have practically. demonstrated that lfullers earth alone, when used in accordance with my previously'mentioned patent, will effectively remove all of these impurities, the carbon, dirt,- water, etc., by mechanical filtration, and the acids, resins and asphaltic matter by .adsorption filtration or refining. But it has been found that to give such a filter the desired life o'r mileage capacity, before replacing the fullers earth, requires the use of a considerable volume of said earth such as to result in a relatively large filrter, which for that reason alone may be inconvenient y'and objectionable for use on pleasure automobiles in particular. I have found that fibrous material such as waste, while effective (and even more so than a like volume of fullers earth) for removing the carbon, dirt, water, etc., by mechanical filtration, is not effective for removing acids, resins and asphaltic matter.

By using, according tothe present invention, both kinds of material, waste and fullers earth or their equivalents, I thereby especially4 utilize those properties of each which render it more effective than the other inKre'moving certain of the impurities; and furthermore, by removing certain of the impurities by one material I make it possible for the other material `to act more effectively and eiilciently in removing the other More specifically, upon the passage of the oil through thev fibrous material (64 in Fig. 1 and 98 in Fig`. 5), the -latter removes from the court tf Appeals oil, principally by mechanical filtration, carbon,

dirt, water, etc. The extraction of those im purities by the brous material has the highly important' additional advantage of preventing said impurities from being carried into the fullers earth where they wouldlodge on the surfaces ofv v the particles and in the interstices between said particles, thereby interfering with or obstructing the adsorption functioning of the fullers earth and materially shortening its yuseful life in tering means of this invention, a fresh charge of pure oil in the lubricating'lystem will be maintained in its original condition during the useful life of the filtering materials; or av charge of oil previously contaminated with impurities will be speedily restored to its original pure condition and thereafter maintained in that condition during the useful life of the filtering materials. In either case, the useful life of the filtering means of this invention vnll, it is believed, exceed by many thousand miles the supposed useful life ofoil lters of the types heretofore most commonly,

used on automobiles.

The method and means of this invention af- Removal of some of the impurities by the fibrous material enables the fullers earth to act with ,greater efficiency in removing other impurities.

The effective life of the fullers earth being thus greatly prolonged, a smaller mass or body thereof may be used. The combined volume of both fibrous material and fullers earth may be considerably less for a given maximum4 mileage of use than when fullers earth alone is used.

While the best results are believed to be obtainable by the use of separate bodies of fibrous material and fullers earth and by circulating the oil through said materials in that order, nevertheless good results are believed to be obtainable by reversing that order. Furthermore, equivalents of said materials may of course be employed. For example, adsorbent materials such as alumina, or carbon, may be used in place of fullers earth and would, it is believed, give good results. But fullers earth is preferred-because it is the least expensive while at the same time highly eflicient.

My aforesaid Patent 1,860,229 shows and describes (p. 2, lines 7-12) small quantities or layers 22 and 23 of wool, gravel or other suitable oil spreading -matei'ial., placed in the top and bottom portions of the casing above and below the body of fullers earth, and states that either one or both of these spreading layers may be omitted. The oil passes through and is spread by said top layer 22 before it (the oil) enters the fullers earth. Upon leaving the fullers earth, the oil passes through the bottom layer 23 which the patent also states p. 2, lines 66-69) may be of waste, wool or the like. It will be apparent that neither of said shallow bodies of material 22 and 23, whether of wool, waste, gravel or other "suitable oil spreading material, would act as a filtering medium or was intended for that stantial length, of compressed fibrous filtering imaterial, an adjacent column, likewise of substantial length, of mineral adsorbent particles,

of a particle size lying between 8.and 60 mesh, less tightly compressed than is said column of fibrous filtering material, a compressible packing layer adjacent that end of the column of mineral adsorbent particles which is remote from the compressed fibrous material column, means for holding the said columns and compressible packing layer under compression, and means for continuously passing oil under pressure from said system during operation of said engine through said column of fibrous material into and through said column of adsorbent material and back to the system.

2. Oil filtering system in the pressure lubricating system of an internal combustion engine,

comprising, in combination, a container, inlet and outlet passages in said container, each communicating with said pressure system, a removable tight covering means for said -container and spaced from said inlet and outlet passages. and a filtering cartridge replaceable through said covering means and positioned 'within said container functionally between said inlet and outlet passages whereby oil introduced under pressure through said inlet passage normally passes through said cartridge in moving to said outlet passage, said replaceable filtering cartridge comprising a columnar casing provided with foraminous end closures and filled with filtering material under compression, said filtering material divided into two adjacent and communicating masses one .of which is a column, of substantial length, of

fullers earth particles having diameters lying between 8 and 60 mesh and the other of which is a column, of substantially equal length, of relatively compact spirally wound layersl of fibrous filtering material the strata of whose .layers are substantially parallel with 'the "longitudinal axis` of the cartridge casing, the outermost layer of fibrous material being adhesvely fixed to the contiguous inner surface of said cartridge casing while permitting the more centrally disposed layers to move longitudinally of the cartridge casing toward the mass of fullers earth particles under the influence of pressure applied against their outer ends.

SOUTHWICK W. BRIGGS. 

